Depending on your dog’s lifestyle and where you live, Leptospirosis may be a major or minor concern for your pup. But what you have to keep in mind is that just like with any disease, as people or animals travel more, it can spread into new areas, and infect new people/pets. In San Diego, Los Angeles, and other areas of Southern California Leptospirosis is not traditionally considered to be a major concern.
However, in recent years we have seen an increase in Leptospirosis and several major “flare-ups” in the local population. Most notably in 2015 LA saw a spike in Leptospirosis cases in 2015, San Diego saw an increase of cases in 2018, and now San Diego is seeing another up-take in Leptospirosis cases in 2020. The hardest part of tracking Leptospirosis in dogs (and people) within a local population has to do with testing and tracking of the disease.
In order to better understand WHY both preventing, testing, and tracking the disease is so complicated you must first understand what exactly Leptospirosis is, how it is spread, and our limitations with testing and prevention of this disease in dogs.
What is Canine Leptospirosis?
Leptospirosis is a bacteria spiral-shaped bacteria that is contagious to both dogs AND people and is spread by local wildlife populations, namely rats. However, there are over 160 different species that can carry and spread Leptospirosis.
To make matters even more complicated Leptospirosis is not contained to ONE or even TWO types. Currently, there are over 260 pathogenic serovars of Leptospirosis, of these we know of ten serovars that cause clinical disease in dogs (Icterohaemorrhagiae, Canicola, Autumnalis, Pomona, Bratislava, Sejroe, Grippotyphosa, and Ballum). Sadly, unlike other diseases and conditions where vaccinating for one serovar will provide immunity across multiple strains of bacteria – this is not the case with Leptospirosis.
How is Leptospirosis spread in Dogs?
The Leptospirosis bacteria are spread through the urine of the infected host, and depending on different factors Leptospirosis can live in the environment for up to 4 months. Transmission of Leptospirosis in dogs occurs by direct contact of the mucus membranes (the gums) with a urine contaminated surface.
This may be through drinking contaminated water, running or swimming in contaminated water/soil/surface then grooming themselves. Leptospirosis can also be transmitted through the bite of an infected animal, or by eating the carcass of an infected animal. If a dog has a but or scrape, Leptospirosis bacteria can enter and infect a dog through that channel. In some rare cases Leptospirosis can be passed during breeding, and during pregnancy to offspring.
Signs of Leptospirosis in Dogs
One of the hardest parts of diagnosing Leptospirosis in dogs is the variability of the clinical signs. Some dogs that we infected with Leptospirosis will just be mildly ill for a short period of time, then they will spontaneously resolve. Others will require intensive care for several weeks before making a recovery. Leptospirosis can also affect several different organ systems – and each system will show its own clinical signs associated with it.
Dogs will start to show clinical signs of Leptospirosis as early as 4 days after exposure, but may not show signs until up to 12 days. Un-vaccinated or dogs under the age of six months will typically show more severe symptoms than older vaccinated dogs.
Clinical Signs of Leptospirosis in Dogs
- Muscle Tenderness
- Reluctance to Move
- Increased Thirst
- Changes to Frequency or Amount of Urination
- Loss of Appetite
- Painful Inflammation within the Eyes
- Bleeding Disorders
- Blood in the Urine, Stool, Vomit, or Saliva
- Pinpoint red dots on skin
Diagnosis of Leptospirosis in Dogs
When your dog is first presenting to a veterinary hospital with any of the above clinical signs, most likely a veterinarian will first run some preliminary diagnostic tests to start to rule out certain diseases and conditions and to give more information as to the severity of the disease so they can recommend what level and type of care would be best for your dog.
Complete Blood Cell Count:
This is a blood test that is done on whole blood, and depending on the veterinary hospital is either run in-house or sent to a third-party laboratory. A typical finding on CBCs for Leptospirosis is something called a “left shift” which is where we see higher amounts of certain types of white blood cells such as monocytes, lymphocytes, and neutrophils. Often we will see mild anemia, or low blood cell count in the results as well.
This is a blood test that is done on blood serum, and depending on the veterinary hospital may be able to run in house or need to be sent off to a third-party laboratory. Results to serum biochemistry can be highly variable depending on which organ systems the Leptospirosis bacteria are attacking in your dog. If the bacteria is causing damage to the kidneys we will see an increase in kidney values such as BUN, CRE, SDMA, along with sodium, chloride, potassium, and phosphorus. If instead, the bacteria is damaging the liver we would instead see liver values such as ALT and ALP. But it is possible to have dogs where both systems are involved.
Due to the range of infection present in dogs it is possible to have a variety of abnormalities upon urinalysis. You may see protein, blood, sugar, puss in the urine or other signs of infection. Urine concentration may be low or high depending on other factors of the disease.
Leptospirosis Specific Diagnostic Testing
Enzyme-Linked Immunosorbent Assay:
There are currently two in house tests that can be performed, the Witness Lepto, and the SNAP Lepto – both are done using small testing kits that can be housed in the clinic. These tests can be very useful as they can provide information to the veterinarian within 30 minutes however, they do have some drawbacks. First is the vaccination can influence the results of these tests – meaning a dog may get a false-positive test if they have been vaccinated. Second is that both tests require a sufficient amount of time after exposure to Leptospirosis bacteria in order to mount a response that would be detectable in these tests. The final drawback of using this method is the lack of knowledge as to exactly which serovar infected the animal to cause clinical disease.
Microscopic Agglutination Test (MAT):
This test is a much slower test, with preliminary results available after several days, and final results after several weeks. The MAT looks at the presence of antibodies to Leptospira bacteria in the dog’s blood. Similar to the Enzyme-Linked tests the MAT test can have a false-positive if a dog has recently been vaccinated within the past 3 months. It may also give a false-negative if the particular serovar is not included in the testing (meaning if your dog was exposed to a new strain of Leptospirosis or once less common to the area, the test could come back negative).
Polymerase Chain Reaction (PCR):
The PCR test looks at the bacterial DNA of the Leptospira bacteria. Unlike both the MAT and the Enzyme-Linked tests which become more accurate with time – the PCR test becomes significantly less accurate after day 7 of infection (from 86% to 34%). Similar to the Enzyme-linked testing the PCR will give a positive test sooner, however, it will not be able to identify the serovar of Lepto, and it can be affected by antibiotics. The great thing about the PCR test in comparison to other testing is that it is not affected by recent vaccination – making it ideal for dogs who have been recently vaccinated.
But which test is better?
The answer to this largely has to do with timing and which serovars are present. Studies have shown that testing at different times after infection occurs makes different tests ideal and that some certain tests are more accurate or sensitive to certain serovars of Leptospirosis than other. Most veterinary hospitals will do a combination of a quick-results test – like either a PCR or Enzyme-Linked – with a longer-form test like the MAT in order to confirm testing. But no test is 100% accurate, meaning that some cases of Leptospirosis will be “suspected” and never confirmed, but dogs will be treated and get better.
Treatment of Leptospirosis in Dogs
Most dogs that are diagnosed or suspected to have Leptospirosis are treated with antibiotics (such as doxycycline) and provided supportive care. Depending on the severity of clinical signs, and the ability for the dog to be separated from the others and humans within the home – dogs may be hospitalized for several days to several weeks. The survival rate of dogs diagnosed with Leptospirosis is almost 80% with proper treatment in care. However, research has shown that certain serovars, such as Pomona, are more likely to cause more severe disease, thus leading to poorer outcomes.
Cleaning after and during a Leptospirosis infection
During the treatment process, it is important to understand that your dog and home are considered contagious during this treatment period – to both DOGS and PEOPLE. This means that while your dog is hospitalized for the first couple of days, you will need to deep clean your home.
There are three types of cleaning solutions that will kill Leptospirosis bacteria…
- Iodine-based disinfectant
- Accelerated hydrogen peroxide
- 1:1 bleach solution
Even once homes have been cleaned, yards or soil is considered contagious for up to 4 months. Thus if you have other dogs in the home make sure you discuss treatment/testing options with your veterinarian. If you have young children speak to your pediatrician about preventative methods, and/or any additional testing that may be needed.
Preventing the Spread of Leptospirosis in Dogs
As a responsible pet parent, if your dog has been to any dog facility (boarding, grooming, training, veterinary) within the past two weeks, let them know that your dog is being treated for Leptospirosis. This will allow the facility to enact strict cleaning procedures, or adjust procedures/protocols in order to prevent the spread of disease. However, there is no legal obligation for them to do so.
If your dog has been to any dog parks or outdoor facilities within the past two weeks, call your local humane society or animal services. Some local jurisdictions will temporarily close dog parks for cleaning and sanitation if a dog with a communicable disease has been in the area.
Depending on your local governments they may or may not ask your veterinarian to report Leptospirosis cases, and may or may not ask for a copy of positive testing information to be added to an epidemiology database to track the disease. This is because Leptospirosis is a zoonotic disease and can be passed to people.
Prevention of Leptospirosis
There are three main ways to prevent the spread of Leptospirosis and limit your dog’s chances of getting this disease. The first is to avoidance – do not allow your dog to drink water from communal water bowls, standing water in puddles, or to swim in lakes. The second is cleaning – dogs are often out and about all day long coming in contact with contaminated surfaces. Having your dog wear booties to protect their feet or bathing them often will limit the amount of exposure they have. Also if you are using a boarding or daycare facility – make sure to do a walk-through and see how they operate – what types of cleaning products do they use, how often do they use them, and does the facility smell “clean” or does it smell like “urine”. The third and final way to decrease the likelihood of your dog getting Leptospirosis is vaccination.
Leptospirosis Vaccination in Dogs
There are two main types of vaccinations currently available for dogs – the L2, and the L4. The L2 vaccination contains the Icterohaemorrhagiae and Canicola strains of Leptospirosis bacteria. The L4 vaccination is more concentrated and contains an additional two strains of bacteria – Australis (containing Bratislava), and Grippotyphosa.
Vaccination does not prevent infection, instead, vaccination works to decrease the severity of clinical signs when/if the infection does occur.
These vaccinations are given in a series of two vaccinations, 2-4 weeks apart, then boostered yearly. Dogs will show a titer to vaccination 3-4 months after vaccination, but immunity via challenge has been established for up to one year. Meaning that only recent vaccination will potentially cause issues with diagnostic testing (as stated above)
Epidemiology reports state that in the United States there are ten known serovars that infect dogs and cause clinical disease. Strain or serovar presence will vary by location, meaning that some areas will see vaccination to be highly effective, whereas others may not. Having a discussion with your veterinary team about the prevalence of Leptospirosis in your area, and which serovars are most common would be ideal to know how effective the vaccination might be.
Safety of Canine Leptospirosis Vaccine
L2: two of ten thousand dogs given the Leptospirosis vaccine will have significant side effects that would require further veterinary treatment.
L4: seven of ten thousand dogs given the Leptospirosis L4 vaccine will have significant side effects.
For comparison purposes – taking Aspirin for people has what is considered “rare” significant side effects (between 1/1000 to 1/10,000).
However, it should be noted that when the vaccination was given in conjunction with other vaccination – like when given in the DAPP-L or the DHPP-L, vaccination related reactions were more likely to occur. Vaccine reactions are also reported more often in smaller breed dogs than larger breed dogs. This suggests that giving the Leptospirosis vaccination separately from other vaccines would be a better choice to mitigate risk.
Risk and Benefit Analysis of Leptospirosis:
Your veterinarian will consider both the risks of potentially getting Leptospirosis against the potential risks/benefits of potential vaccination prior to making their recommendations. If at any time you do not understand your veterinarian’s reasoning for recommending a certain course of action for your dog – don’t be afraid to ask questions – YOU are your dog’s best advocate!
I know decisions like this can be particularly difficult, especially when we don’t have all the information – just know that your veterinary team is here for you to answer questions/concerns that you have. If you ever feel like you are not being respected during an appointment or do not feel comfortable – it’s okay to look for another veterinarian to get a second opinion. Sometimes one veterinarian’s communication methods will not “mesh” well with yours – and that is OKAY.
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‘Til next time my Canine Health Nuts!
Today’s Veterinary Practice, “Leptospirosis in Dogs: Diagnosis, Treatment, and Management”
Today’s Veterinary Practice, “Canine Leptospirosis: (Still) an Emerging Infection?”
Today’s Veterinary Nurse, “Leptospirosis in Dogs”
Mereck Veterinary Manual, “Leptospirosis in Dogs“